docs: def canonicalization(self, method, node):
          """
          Canonicalizes a node following the method
          :param method: Method identification
          :type method: str
          :param node: object to canonicalize
          :type node: str
          :return: Canonicalized node in a String
          """
          if method not in constants.TransformUsageC14NMethod:
              raise Exception('Method not allowed: ' + method)
          c14n_method = constants.TransformUsageC14NMethod[method]
          return etree.tostring(
              node,
              method=c14n_method['method'],
              with_comments=c14n_method['comments'],
              exclusive=c14n_method['exclusive']
          )